Re: 2.6.24-rc4-git5: Reported regressions from 2.6.23

Stefano Brivio
2007-12-19T01:00:54Z

On Tue, 11 Dec 2007 10:01:20 +0100
Ingo Molnar <mingo@elte.hu> wrote:

> ok, just to make sure we are all synced up. I made 8 patches related to
> this problem category (and all the trickle effects). 3 are upstream
> already, 5 are pending for v2.6.25. One out of those 5 is an immaterial
> cleanup patch - which leaves us 4 patches to sort out.
>
> So i'd suggest for you to try latest -git - that will tell us whether
> udelay() is acceptable on your box right now.
>
> i've attached those 4 patches:
>
> x86-sched_clock-re-scheduler-fix-x86-regression-in-native-sched-clock.patch
> x86-cpu-clock-idle-event.patch
> sched-printk-recursion-fix.patch
> sched-printk-clock-fix.patch
>
> none of them is _supposed_ to have any effect on udelay(), but the
> interactions in this area are weird.

Exactly, none of them have any effect on udelay().

> [ note: CONFIG_PRINTK_TIME will be broken and only fixed in v2.6.25, so
> use some other time metric for determining mdelay quality. ]
>
> plus then there's this patch:
>
> http://lkml.org/lkml/2007/12/7/100
>
> is it perhaps this one that fixed udelay for you? [ which would be much
> more expected, as this patch changes udelay ;-) ]

Yes, this one did. mdelay(2000) still gives delays between 2 and 2.9s, which is
acceptable. I have marked the regression as CODE_FIX.

--
Ciao
Stefano